Mr. Kicillof’s jab came after Standard & Poor’s Ratings Services said Argentina had defaulted on some bonds, triggering a downgrade of the country’s foreign currency credit rating.

Meanwhile, rivals Moody’s Investors Service and Fitch Ratings have been silent on their Argentina stance, after an agreement could not be reached late Wednesday.

The situation shares some similarities with the 2011 downgrade of U.S. debt, when S&P was the first firm to take a bold stand on a sovereign rating and draw the wrath of government officials.

But there are differences. Unlike the surprise surrounding the U.S. downgrade, S&P said it had been signaling Argentina was at risk of a downgrade since June 30, when Argentina failed to make a $539 million interest payment to bondholders. At the time, S&P said it would downgrade Argentina if after the 30-day grace period—which ended late Wednesday—the bond holders had not received payment, according to the firm’s ratings rules.

“For us, yesterday the bond holders didn’t receive the funds and that’s a default,” said Sebastian Briozzo, an S&P analyst based in Buenos Aires, in a phone interview.

“It’s a fact: the government is not paying. If the government begins paying again, we’ll remove the rating,” said Mr. Briozzo, adding there was never any contemplation on not issuing the downgrade.

Analysts and investors said Argentine bonds didn’t react explicitly to S&P’s default call. Instead, bondholders are focusing on the odds of a potential deal with banks that could settle the conflict with the holdout and allow Argentina to pay all of its creditors.

Moody’s is still reviewing its stance on Argentina’s holdout bonds. The reviews have no formal deadlines, though they generally do not last more than 90 days, said Eduardo Barker, a Moody’s spokesman. But “a conclusion can come much sooner than that timeframe,” Mr. Barker said.

Another factor: Moody’s does not have an outright default rating. Its credit grades measure not only the likelihood a bond defaults but also the expected losses. The review will determine whether Moody’s will downgrade Argentina and if it considers the bonds in default.

Moody’s rating for Argentina is Caa2, three notches from the lowest rating it can issue. But the decision won’t be based only on Argentina bonds defaulting, but rather the expected losses.

Fitch did not issue any update to its Argentina rating on Wednesday or Thursday. A spokeswoman did not immediately respond to requests for comment.